During the construction process, especially the commercial or industrial construction process, after a foundation has been laid, a structural steel frame is erected to support various floor, wall, and roof systems. This structural steel frame erection process begins with the erection of a plurality of vertical structural steel columns, such as square columns or columns having flanges (I-columns) on the foundation. These vertical structural steel columns are joined together by a plurality of horizontal structural steel beams, such as girders or beams having flanges (I-beams). The vertical structural steel columns and horizontal structural steel beams are connected via bolts and/or welds to form vertical frames for the placement of wall systems and horizontal frames for the placement of floor and roof systems. At each level of the structure, it is necessary to access the tops of the vertical structural steel columns to position, bolt, and/or weld the horizontal structural steel beams to the columns.
Heretofore, the procedure for accessing the intermediate levels and tops of the vertical structural steel columns involved bracing a ladder against each column, using a personnel lift, or riding on one end of a horizontal structural steel beam supported by a crane cable. All of these procedures are marginally safe, inconvenient, and time consuming, and thus expensive. For example, using a ladder at ground level is, to some extent, acceptable from a safety standpoint. However, moving the ladder from vertical structural steel column to vertical structural steel column is inconvenient and time consuming, requiring a worker to adjust the feet of the ladder on uneven ground and often work from an unstable position. These problems are compounded at higher levels, where it is often necessary to balance the ladder on horizontal structural steel beams and move the ladder to subsequent vertical structural steel column locations by walking the horizontal structural steel beams while carrying the ladder. Personnel lifts are, in general, expensive to rent and operate and it can be expected that the ground at a construction site will be uneven, interspersed with plumbing and electrical stubs and various other obstructions that cause interference. In addition, operation of a personnel lift becomes obstructed to a greater degree at higher levels by intermediate-level horizontal structural steel beams, requiring up-and-down operation of the personnel lift bucket to move to subsequent vertical structural steel column locations. Finally, riding on one end of a horizontal structural steel beam supported by a crane cable is dangerous, unstable, awkward, and not conducive to horizontal structural steel beam alignment and placement. This procedure is no longer accepted in the present safety-conscious construction industry.
Alternative column climbing devices for climbing structural steel columns and the like, such as square columns and columns having flanges (I-columns), are known to those of ordinary skill in the art. A number of these column climbing devices are worn on the feet of a user, like a pair of climbing shoes. However, each of these column climbing devices suffers from at least one of a number of problems that makes the device difficult or impossible to use and, more importantly, inherently unsafe.
For example, U.S. Pat. No. 1,260,856 (issued to Bates on Mar. 26, 1918) discloses a climber for flanged metal poles consisting of a foot plate, means for securing said foot plate to the foot of a wearer, a member fixedly secured to said foot plate in the medial line thereof adjacent to the heel and offset from said medial line adjacent to the toe, said member having an upwardly and inwardly directed end carrying a point contact in the medial line of said foot plate to engage one side of the flange and means on said member spaced apart from said point contact to engage the other side of the flange.
This configuration makes the column climbing device difficult or impossible to use and inherently unsafe. Because a point contact is used to engage the back side of the flange of the beam, and all of the friction holding a user in place along the height of the beam is focused at this point contact, a dangerous fulcrum effect is created. Any rotational motion of the user's foot (which is inevitable and unavoidable while climbing and/or performing tasks) potentially disengages a portion of the line contact that is used to engage the front side of the flange of the beam, leaving only a point contact engaging the back side of the flange of the beam and a point contact engaging the front side of the flange of the beam. This is inherently unstable. In addition, the line contact that is used to engage the front side of the flange of the beam is subject to very high shear forces, making its failure more likely. Further, the column climbing device consists of a plurality of components, making its manufacture more difficult and, again, its failure more likely. Because this and other conventional column climbing devices are adjustable, via bolts or otherwise, it is difficult to maintain the relationship between the point contact and the line contact, for example, making these column climbing devices inherently dangerous.
Similarly, U.S. Pat. No. 1,312,399 (issued to Heywood on Aug. 5, 1919) discloses a column climbing device consisting of a body formed as a single casting and including a flat plate portion, a laterally-extending u-shaped yoke formed integrally upon one end of said plate portion, the upper edge of said yoke lying in the same plane as the upper surface of said plate portion, a pair of depending ears formed at the juncture of said yoke and said plate portion, a set screw threaded through the extremity of said yoke and extending towards said plate portion substantially in alignment with the longitudinal axis thereof, and a pair of set screws threaded through said ears and extending in a direction opposite to that of said first named set screw, said last named set screws being in a spaced-apart parallel relation to one another and to said first named set screw.
Again, this configuration makes the column climbing device difficult or impossible to use and inherently unsafe. Because a point contact is used to engage the back side of the flange of the beam, and all of the friction holding a user in place along the height of the beam is focused at this point contact, a dangerous fulcrum effect is created. Any rotational motion of the user's foot potentially disengages one of the two point contacts that are used to engage the front side of the flange of the beam, leaving only a point contact engaging the back side of the flange of the beam and a single point contact engaging the front side of the flange of the beam. This is inherently unstable. In addition, the column climbing device consists of a plurality of adjustable components, making its manufacture more difficult and its failure more likely.
U.S. Pat. No. 3,111,194 (issued to Erwin on Nov. 19, 1963) discloses a column climbing device consisting of an elongated rigid bar having a beveled inner end defining a biting edge, an elongated spacing member mounted on said bar, a first fastening means and a second fastening means detachably securing the spacing member to the bar, footwear engaging means attached to the first fastening means and the second fastening means and adapted to secure a climber to an item of footwear with the bar and spacing member disposed under the footwear sole and crosswise thereof and with said inner end protruding from an inner side of the footwear, said first fastening means being disposed adjacent to said inner end, a column binder including an inner leg, an outer leg, and an intermediate portion connecting corresponding ends of said legs and combining therewith to define a recess between said legs closed at one end by said intermediate portion and having an opposite open end, said inner leg being engaged by said first fastening means for securing the column binder immovably to said bar and spacing member, said outer leg having an inner biting edge disposed parallel to said biting edge of said bar and spaced outwardly and upwardly therefrom and adapted to engage an inner surface of a flange of a structural member the outer surface of which is engaged by the biting edge of the bar when the flange is received in said recess between said inner bar end and said outer leg.
Again, this configuration makes the column climbing device difficult or impossible to use and inherently unsafe. Because a line contact is used to engage the back side of the flange of the beam and a line contact is used to engage the front side of the flange of the beam, and because these line contacts are hinged and not disposed in a fixed parallel relationship to one another, a dangerous friction-release scenario is made possible. Any rotational motion of the user's foot potentially disengages a portion of the line contact that is used to engage the front side of the flange of the beam and/or the line contact that is used to engage the back side of the flange of the beam. This is inherently unstable. In addition, the hinge mechanism that structurally connects the line contact that is used to engage the front side of the flange of the beam to the line contact that is used to engage the back side of the flange of the beam is subject to very high shear forces, making its failure more likely. Further, the column climbing device consists of a plurality of components, making its manufacture more difficult and, again, its failure more likely. Still further, because, in this embodiment, a user's feet are next to a column being climbed, as opposed to in front of it, the user's center of gravity does nothing to maintain the line contacts described above and a dangerous twist-off scenario is made possible. A lever arm is created in the wrong direction.
U.S. Pat. No. 4,368,801 (issued to Lewis on Jan. 18, 1983) discloses a climbing device for climbing columns such as columns having flanges. The devices are worn in pairs on the feet of a climber and each is equipped with a gripping member having spaced-apart jaws adapted to grip the column flange. The gripping member on each device is mounted on the foot-attached or base member for selective swinging between two positions, one a climbing position in which each pair of jaws extends laterally-inwardly of the respective foot and the other a retracted position in which the jaws extend laterally-outwardly and behind the heel of the climber's foot so as to be out of the way when not used for climbing. Means are provided for selectively locking the gripping member to the base member in either of said positions.
Again, this configuration makes the column climbing device difficult or impossible to use and inherently unsafe. Because a plane contact is used to engage the back side of the flange of the beam and a plane contact is used to engage the front side of the flange of the beam, a dangerous friction-release scenario is made possible because the friction holding a user in place along the height of the beam is distributed over too large an area. This is inherently unstable and the user's weight is insufficient to provide enough friction force to hold the user in place along the height of the beam. In addition, the column climbing device consists of a plurality of components, making its manufacture more difficult and its failure more likely.
Therefore, what is needed is a column climbing device for climbing structural steel columns and the like that overcomes the problems described above. What is needed is a column climbing device that is relatively simple to use and inherently safe. What is also needed is a column climbing device that is relatively simple to manufacture and the failure of which is unlikely.